@dc110 - that is old data, and many of the posters on this thread, myself included, will have seen it before and various other tests over the years.

A couple of points made earlier in the thread but worth reinforcing:

- how a tubular is mounted (tape, glue job) has an effect of rolling resistance

- from memory the Tour data you've posted used latex tubes in the lowest crr clincher results (eg. Vitt Evo) ... the point being of course that this is not safe with a carbon clincher. So for once at least, apples vs. apples is not apples vs. apples.

The right comparator with carbon rimmed wheels is butyl inner tube for clincher vs. either latex or butyl inner for tubular. That disadvantages clinchers vs. data such as you've posted.

Finally, I wouldn't be so convinced by the Tour data. It's one data set and their testing results can throw out some pretty strange results too ... see the recent wheel test in which aerodynamically the Campagnolo Eurus outperformed numerous deeper wheels - I think including the Zipp 303.

How odd! Lesson is to look at a range of data sources and know what you're comparing.

On that basis I don't think you can conclude as things stand that clinchers have lower crr. Certainly when the need for butyl tubes is factored in, there is no advantage, and probably a disadvantage.

As far as rolling resistance some manufactures, namely continental and Vittoria claim their testing has shown clinchers to be superior. There are also some other tests, such as the one conducted by Tour, and roues artisanales (conducted at continentals test facilities) that show a noticeable advantage with clinchers. Comparing the spread in the later test between the best clincher and best tubular would indicate you are giving up nearly 16 watts with tubulars.

Now Al Morrison has done probably the most comprehensive testing of road bike tires out there, and his tests show a slight advantage in favor of tubulars. That said he is using vastly different equipment and test protocols, and no disrespect to him and all the hard work he has put into it, but for my money I'm going to go with what the multi-million dollar R&D facilities are showing, and not some guy with rollers in his garage.

Except Al Morrison documents everything: how he glues the tubulars, how he controls for temperature, how he does the measurement. Since we've established glue technique matters, without knowing the glue technique used by the magazine, how can we be sure the results are fair?

For example, I might conclude using tape is the best comparison, since it's reproducable, and glue has innate variability. But we know tape yields worse Crr. Or using no glue at all is reproducable, but gives poor Crr, perhaps counter-intuitively to many.

Note the tire manufacturers have a profit interest in this. Al Morrison has none.

"Absolute" - I'm not sure about absolute, but so far the cases of 'carbon clincher tire failure' have involved either very early carbon clinchers (read: a few years ago) and/or latex tubes in situations with heavy braking, such as that potent mix of steep descent and non-confident descender.

Riding them on flat courses? You might be ok, but not a guarantee. Latex tubes feel great (phrasing) but they tend to overheat (again, phrasing).

Even if clinchers did have a lower Crr, which for reasons being discussed right now is arguable, they still don't give the same overall ride characteristics of a tubular. There's a reason clinchers haven't taken the place of tubulars in the Grand Tours. If they were even close, you would see them a lot more often than you do simply because of the ease of mounting a clincher versus a tubular. But that, in my opinion, is where the advantage ends as far as ride and performance is concerned. I only wish I had the good fortune to have been able to use tubulars when I was younger.

For purposes of what I base my opinion on, I'm comparing a set of Hed Belgium clinchers mounted with Continental 4000s (23mm) to either Campagnolo Bora Ultra Twos mounted with Veloflex Carbons (22 and 23mm), Continental Competitions (22mm), or Veloflex Roubaix (24mm). And on the low profile alloy front, Ambrosio Nemesis rims with Veloflex Roubaix 24mm).

I just feel a whole lot more confident riding the tubulars in any of the above configuration than the clinchers.

Not trying to further egg on another endless debate about tubbie vs clincher but rather point out a very popular resource and what they say in a 3 part series (from 2012) about crr testing......in part one they note that at Slowtwitch.com (with a huge triathlete following) and amoungst their readers there is a lot of faith in Al Morrison's testing - and that their real world experiances back it up.

- the elasticity of latex making them inherently less suited to a non-closed system (cf tubular casing with clincher rim+tyre)

On the flat you remove the first problem, but not the second. Some people manage latex plus clincher set-up no problems, and other experience more blow outs than with butyl inners. Careful installation is no doubt an explanatory factor.

If you successfully ide latex plus clinchers on the flat with non-carbon clinchers, then no reason why you won't be ok on the flat IMO.

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